Sinful Desire
by Minatsuchan
Summary: What if Miyuki stepped out of the border line as Tatsuya's 'Younger sister? Will it make big changes between them or not? If Miyuki's desire get's even worse, what will Shiba Tatsuya do? (Sorry I'm REALLY bad at summaries, please read and rate!) (Rated T for some things).
1. Chapter 1

Don't own the anime.

Please enjoy and leave a review!

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**Sinful Desire**

**By: Minatsuchan**

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For a long time. This feeling of mine never left my heart for the longing years I've waited.

It's hard and at the same time painful. Every night, alone in my room. I always cried out, but even so..._no one will hear me._

Onii-sama, what rather would you do if I, your beloved younger sister has a forbidden yet sinful desire of having you as my partner not just my brother? But even so, I don't have the courage to tell you how and what I really feel.

Because I know, that you. As a perfect brother of mine will never cross..._the border line as my brother._

But I'd rather die that having this pain inside my heart be buried even deeper.

From the day I started calling you, 'onii-sama'. I've decided not to show what I am feeling for you. But as I can dictate and observe. You are already aware how I feel whenever I'm around or you're by my side. But you never spoke a word about it and dodge the subject immediately.

**Incest...**

For another meaning of, A forbidden love between two related bloods.

I know-no, I knew right from the start that, you won't return my feelings no matter how many times I show it so obviously..._onii-sama...Am I...disgusting?_

Oh yes, Onii-sama. Do you remember that time when I almost kissed you? You were sleeping on the couch, but my conscious stopped me, but when you opened your eyes, I was surprised that my hand slipped and resulted for our face to have an inch distance.

You heard it didn't you?..._my crazy heart beat._

"Miyuki? Are you alright? You look pale today, you should tell Tatsuya about it." from my left side, I heard Mizuki suggested. I simply shake my head then leaned my chin onto my hands.

"I'm alright, just didn't have much sleep." I wonder...how can I keep this smile even though deep inside...I feel lonely?

"Then please, I suggest that you should go to the infirmary room. In Miyuki's condition it might get worse," she added as I give up. My friends worry too much, but gladly I have friends who'll support and give me such advices. Warm smiles, true laughs, and unforgettable memories.

I don't want to bother Onii-sama, I don't want to cause him any more trouble. Now that I freed him from his rein. My power is now unleash like Onii-sama's power. I can protect myself...but how can I if I'm afraid of hurting those bad people? Onii-sama is always there to comfort me and always telling me it's alright. But what if one day, you won't be able to stay by my side anymore? I know I'm selfish but I don't know what I would do.

But even so, I preferred my power to be sealed...because I have feared that if my power is now released, I might hurt those people around me unconsciously...and I might hurt Onii-sama too.

But...I don't want to go back to that place again. And that is in the Yotsuba resident and my aunt's home.

Oba-sama is strong and powerful, yet her powers are terrifying. People doesn't call oba-sama **'Queen of night' **for nothing.

I didn't like how Oba-sama treats Onii-sama as my bodyguard or a guardian. Because his my brother and not just a guardian.

"Alright, thank you Mizuki-chan. Please inform the others if they searched for me," she nodded happily as I excuse myself. Gladly it was break time, I was able to take a deep breath and sniff a relaxing breeze out here.

As suggested I headed to the infirmary room.

_"Are you sure?" _I stopped when I was about to reach the door knob when I heard a voice which was familiarizing as Onii-sama's voice.

_"Yes, I'm alright Tatsuya-kun, thank you. You can leave me now," _with no surprise, it's Honoka-chan's voice. Without noticing I already left the front door and headed back to the table where Mizuki's seating in.

*Throb, throb*

What pain is this? Besides, I'm not in a rightful position to be involve in Onii-sama's private life.

**Normal P.O.V**

Miyuki seated down and clenched her hands.

"Oh, why are you here Miyuki-chan?" A surprised Mizuki asked. They still have 8 minutes until their break time is over.

"N-nothing, I just felt better already. I'm just hungry," she continued on smiling like she always do, and yet nobody noticed how forceful it was.

Miyuki already notice that Honaka has a feeling for her brother. So she's out of it, it's her brother's private life not her's.

She never crossed the border line because she knows that once she stepped out, everything will immediately change.

~~**AFTER CLASS~~~~**

Miyuki was currently walking, she was heading for the student council's office.

She wobbles as she walks, she's now recalling the nightmare she had last night, and that might be the reason why she's pale. And yes it was indeed a nightmare.

A dream that when her power was finally unleashed and that is she's now losing the power to control herself. She inherited that kind of power from her aunt and mother. Yet it was far more different.

"Excuse me, can I speak to Onii-sama," her voice almost cracked.

"Miyuki? What's the matter?! Your pale!" Mayumi-senpai squealed as that voice reached Tatsuya's ears.

He immediately stood up and hurriedly ran towards Miyuki's side.

"Are you okay Miyuki?! Does anything hurt?" She chuckled. She never saw this kind of side of his brother, because his face always shows and describe nothing but calmness.

"Onii-sama, you're over exaggerating. I'm alright, I just need some rest." she exclaimed as Tatsuya's expression worsen.

"Then Miyuki go home and rest, I won't be able to return home early because of things I need to finish but I promise to be home soon," Miyuki just smiled and bowed down for her leave.

_"Alone again...huh?" _she sadly stated to herself.

She didn't waste anymore time and headed home as he brother ordered her to do.

She's tired and has the desire to sleep. So when she immediately reached their house, she locked the door and headed to her room and slump herself onto her bed.

But she needs to change her clothes so she stood up once again and opened her closet to change her clothes.

After that, she headed back to her bed and insist herself to fall asleep, but the truth was...she can't sleep because her brother's not home yet, but since she was told to sleep, she won't disobey his brother and will sleep even if she doesn't want to.

...

...

...

...

*Bathump, bathump, bathump.*

_"What...is this?" _she groaned as she felt her body getting hotter.

She opened the air conditioner but it was no use, she used her ice to cool herself but it's useless too.

And she was sweating nonstop!

"What is going on?!" she panted as she swiped her sweat off. but it was still dripping.

_"Miyuki! I'm home!" _She sat up immediately when she heard her brother called out.

Her body was beginning to feel hotter and hotter.

"Onii-sama?! I-I though you'd be home quite late?" she stammered as she shivered at the same time, she's getting nervous now.

She stood up and headed downstairs and at their living room she saw his brother on the couch, her heart beat was racing faster and she was panting.

**"That's it...Miyuki...follow your desire," **she flinched when she heard her inner self spoke to herself.

_"No, Miyuki! She's your brother!" _she fight off...but her eyes was only capture by his brothers lips.

She felt comfortable staring at his brother's relaxed sleeping face...and without noticing Miyuki was walking nearer and so was her face to Tatsuya's face.

...

...

...

*Dimp*

And now, her lips was pressing against his...Tatsuya immediately felt it so he shut his eyes open, and instead of pushing Miyuki away, his eyes was aroused on how Miyuki's face flushed deep red and her body sweating.

Without noticing, Miyuki's lips was moving and her tongue was slipping in...and now their walking through the process of french kiss!

Tatsuya didn't let Miyuki move any farther so he made his action.

***SHOVE***

"Miyuki!" she immediately snapped out of reality when she heard his brother's angry voice.

"I'm..Sorry," her body was trembling and her legs couldn't move.

"Miyuki! What have you done?! Please consider that were.._siblings!"_ It sting right through her heart.

She crossed the line.

"Hontonigomenasai...I'm unforgivable for having this desire onii-sama...and _...I'm disgusting aren't I?_" Tatsuya flinched...not only the reason that Miyuki was crying but how desperately in pain her face was.

"Miyuki―" before he can protest, Miyuki immediately run off upstairs towards her room.

"Miyuki!" He called out but she didn't turn around.

He shuffled his hair and swiped off his lips.

_"Miyuki...Why did you show me that kind of face?"_

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**G-Gomenasai! Sorry if the story is not that good, but hopefully you all like it! Erm...I guess it's rated T. Sorry about that, please comment on how the story was, should I continue? Or not? and I'm sorry if the characters are way too OOC!**


	2. Chapter 2

**Don't own the anime.**

**Please enjoy and leave a review!**

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**Sinful Desire**

Chapter II

By: **Minatsuchan**

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_"Disgusting..." _

_***Throb, throb***_

_**"**Such a disgusting creature!" stop it..._

_"How can she feel that way to her own brother?" please...Stop it already!_

_I know! I don't want to hear it anymore!_

***SNAP***

Miyuki sat up vigorously, sweating, panting, and finally she was gripping her bed sheets tightly. The same nightmare this past 2 days is still haunting her. She tried to calm herself down and prevented herself from shredding tears, because she know herself that it won't resolve anything.

She looked at the side of her table to look at the time which was 1:39 AM and it's already past midnight. Same time she wakes up these past two days.

She was able to calm down yet her heart was still thumping from the very bad dream.

_"Nightmare again...I guess this is my punishment for doing something forbidden," _She stated as she stood up and headed down stairs towards the kitchen to get some water in the refrigerator.

As she reached for the water jug she noticed how her hands trembles, she put the jug down because she thought that she might break it and cause a large sound that will reach her brother's room.

She knows that her brother is already asleep so she'll be careful so she won't wake him up.

When she was young, whenever a nightmare comes by. Her onii-sama is the only one who stays by her side and the only one who says that, 'Don't worry, I'm right here until you fall asleep,'

But right now, there's nobody in the house she can run into to make her feel that the nightmare will go away.

Her hands wasn't trembling anymore so she poured the water into the cup then putted the jug back to the refrigerator.

She stared at her reflection in the water, she thought how coward she was for avoiding her brother the same past two days.

_"How can I face my brother now? I know that running away won't solve anything either, but whenever I see nor stand near onii-sama, a flashback which I kissed onii-sama always shows up." _She stated as she gulped down some small amount of water.

From the right side of her position, there was mirror. She walk forward and stared at her reflection.

Her skin was pale compare to her usual colored milk skin. She's not getting enough sleep thanks to the nightmare that always shows up whenever she close her eyes to sleep.

She drink all the remaining water in the glass, headed to the sink and washed the cup and put it in it's own container.

"Thank you Tatsuya-kun, I'll be heading home since it's late," as soon as she heard a voice she hid behind the table. Her heart was beating faster and she noticed that it was a girl's voice, far more it was Honoka's voice!

"No, I'll drive you home since it's already past midnight and it's dangerous if you commute," and that was her onii-sama's voice.

She peeked at their direction to see how Honoka blush, and as she observed her clothes. She was still wearing their uniform.

Many questions begun rotating in her mind.

_"What's Honoka-chan doing here?"_

_"Why's Onii-sama still awake?"_

_"Why's Honoka's clothes full of wrinkles and it's crumpled?"_

She couldn't think straight anymore so as soon as she heard the door shut. She quickly run upstairs and headed to her room.

...

...

...

She immediately shut the door and slump herself in her bed and buried her face in the soft pillow.

"Why am I getting all furious for? Besides...Onii-sama's private life is not my business is it?" she's getting confuse. She don't know which will consume her, her desire/jealousy or the role as a younger sister.

If she takes both...Something bad will surely happen. And she knows it.

Today was Saturday, so she'll stay in her room for the whole day.

She closed her eyes and feel the warm air that was swirling around her room, hearing the 'tic, toc' sound that was coming from her alarm clock. She didn't want her life to remain this way, if she don't do anything soon. Probably, her life will remain the way it is right now.

She knows her brother pretty well, whenever she pulls a prank on her onii-sama, which her feelings are included. She just...States that 'Sorry onii-sama, my prank went too far,' but she guess that she can't state those words since the prank was far more risky.

"I know that Onii-sama will act the same as always...Like nothing happened, I guess that's how far Onii-sama takes his role as my, 'brother'." She covered her eyes with her arm, she bit her lower lip,meaning that she's preventing herself from crying again.

"It's so tiring to pretend," she stated.

But when the flashback of Honoka and her onii-sama are together, her heart was throbbing in pain. Like she wants all her brother for herself.

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-**6: 00 AM-**

_"Miyuki, breakfast is ready," _She flinched when she heard her brother spoke on the other side of the door, she didn't get to sleep until now, since she can't get the event last night out of her head.

But her heart was thumping faster again. If she didn't ate breakfast, surely her brother will get angry.

"Yes, onii-sama! Please go on ahead I'll just change my clothes," She replied as she stood up and headed towards her closet, she pulled out a simple black leggings and a white t-shirt.

Her heart was still racing, it might be awkward since she cannot face her brother properly.

So as soon as she was done dressing up, she headed out towards the table in the kitchen, she saw how deliciously arrange the breakfast was.

"Good morning Miyuki," She flinched when she heard her brother greeted, she smiled. Not letting her brother notice how anxious and nervous she was.

"G-good morning, onii-sama," She greeted back. Like Miyuki said...Her brother was acting like always.

"Oh right, Miyuki. I'll be heading out later, I'll accompany Honoka to the mall." As she sat down, she clenched her hands together.

_"Leaving me alone again..." _She thought sadly as she bowed her head down.

"O-onii-sama, is it alright if I come along?" She requested.

"Eh? Sure why not?" Her brother replied as Miyuki smiled.

Tatsuya sat down and they ate breakfast like always. But still, for Miyuki, the air pressure was too awkward. There's a big silence between them so she's getting uncomfortable eating.

When she was done eating, she excused herself as she put her dishes in the sink and headed upstairs.

_"Not the same as before...For me that is," _she stated as she locked the door in her room, leaving her brother that was still eating.

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**{Time skipped}**

"Miyuki, are you ready?" Tatsuya asked as she nodded. Right now their inside the car while Tatsuya was driving.

They were heading to Honoka's house to pick her up.

When they reached the other side of the neighborhood, Honoka was already waiting in their gate.

"Good morning," She greeted as the two of them greeted her back.

As Miyuki expected, Honoka will take a seat in front beside her brother. More likely, she chose to seat at the back since there's nothing to talk about with her brother. Usually she always seats in front right beside him.

For the whole trip, she stayed quiet as Honoka and Tatsuya spoke nicely...while she's getting out of place.

They headed to the parking lot and ride off the car. Miyuki remained silent as they entered the mall's entrance. She stopped on walking and let the two of them lead farther from her.

She stared at her surrounding...Nothing but black and white. Whenever she comes here with her brother, her surrounding is so colorful.

"Miyuki?" She turned to see her brother who was right in front of her, along with Honoka.

"A-ah, I'm really sorry, I doze off a bit, let's go?" She smiled like she always do...Yet he doesn't how much it hurts her inside.

Shopping, eating, playing in a arcade game.

She's still behind them. And finally she had enough, it was already 11:45 AM.

"Brother, I'll be strolling the mall, if I'm going home I'll just text you," Miyuki was about to walk away when Tatsuya caught her arm.

_"Miyuki...Just called me Brother," _He mattered, he knows that there's something wrong when Miyuki call her like that.

"We'll come with you-" before he finish his words, Miyuki trailed him off.

"I'm sorry Onii-sama, but I can't afford to ruin your _date_." She smiled as she break off the grip and walked away. He was about to run after her when Honoka stopped him. He stared at her but when he turn around to see Miyuki, she's already gone.

Miyuki lied, she's not in a mood on strolling the mall. So she headed straight home.

"Coming along was a very bad idea, after all." She sadly spoke.

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It took minutes until Miyuki reached her destination. She commute that's why it took quite a long time.

When she unlocked their house she immediately locked it and headed to her room.

And she cried and cried. Not noticing how time flies.

When she opened her eyes...She didn't notice the she fell asleep, she looked at her clock to see that it's already late, 'having fun huh?' Miyuki giggled...Not happily but sadly.

She heard the door opened, which means that her brother was already home.

She can hear footsteps coming near her room.

***Knock, Knock***

"Miyuki, please let me in." she covered her ears and turned around, but she knows that her brother will be right there until she open the door for him.

"Is there anything I can help you Onii-sama?" she walk in front of the door, which was facing Tatsuya on the other side.

"I need to talk to you," He spoke on the other side.

"Onii-sama, if it's about earlier then it's alright already," She giggled.

"Miyuki! Open the door this instance!" Tatsuya yelp out getting impatient.

...

...

...

"See onii-sama? You're always like that...Did...you...ever one considered how I feel?" Her tears failed to be kept, it streamed down her cheeks as she opened the door.

"Miyuki..."

"Can I ask what Honoka-chan's doing here last night?" She cried.

"She just requested for me to observe her data," He replied.

"I thought that the one you'll be observing data is only me?" She added, while her tears was still streaming non stop.

"Miyuki! Stop being selfish!" his expression was getting more and more confused.

"Yes, onii-sama! I'm selfish! Because I-" Before she can continue Tatsuya trailed her off.

"Miyuki! Don't talk any farther!" He yelled as Miyuki's eyes widened...She bowed her head down and pulled her brother in to her room and slump him on the bed.

"Why onii-sama?! WHY?!" She punched his chest as she leaned her head onto it.

"Then please...If you find me disgusting please tell me straightly...Onii-sama, I don't want to expect any father!" She yelled as she raised her head and put her hands on Tatsuya's cheeks, and was about to land her lips onto his when Tatsuya grabbed her arm and flipped there positions, now Miyuki is the one whose cornered.

"Miyuki!" He angrily called.

"I see...So...Onii-sama don't want to cross the line huh?" Tatsuya gasp...Miyuki's expression was starting to get more and more twisted.

"Well, then _onii-sama. _You find me disgusting right? Then if you do, please say it to my face. And if you don't. Then please kiss me, that way. I won't show my affection nor myself to you ever again," her bangs covered her eyes. her tears was still falling down.

"Miyuki, stop thinking about-" He was trailed off when Miyuki spoke.

"Please...Onii-sama...I'm so tired...Please try considering what I'm feeling right now. I guess you won't even feel how my heart ache, how my heart throb in pain whenever you dodge this kind of conversation, like the times I always say that this is only a prank, like the times I always smile. Does onii-sama know how this feeling breaks me? How it kills me inside?" He remained silent, this is the reason why he always dodge this kind of conversation. It's getting far more risky.

"Please choose onii-sama, whether you'll say it, or you'll put it in action."

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**Sorry. If the scenes are like that and Miyuki is OOC. Please review and rate ^^ I just ship for TatsuyaXMIyuki. Please tell me should I continue of not?**


	3. Chapter 3

**Hello again! I'm very very sorry for the very late update, our exam has ended and my schedules are not that pile up anymore yet, school projects and assignments won't be avoided so I really hope you'll wait for the chapters.**

_Thank you for the lovely reviews and votes! And if there is a part that is quite different from the novel, manga or anime, I'm sorry about that but, my idea from this story is a bit different so please don't hate me._

_(Sorry for the short chapter, just an introduction for the coming chapters. Hurtful chapters :()_

Sinful Desire

_**Chapter 2.5**_

I looked at Onii-sama's honest eyes. It really never wavers nor show any kind of reactions usually. But now, I can see how nervous and anticipated he's getting. My heart beat is still beating faster and my legs were already trembling.

I really want to run to my room but, I must resist and hear what Onii-sama's answer is.

"Please answer honestly Onii-sama," I added as he looked at me with a very confusing expression.

"Miyuki…I…" onii-sama's hesitating…And with my heart throbbing like this, I already know what he's going to say.

After a blink, I felt his lips pressing with mine. My eyes widened, and I never expected that onii-sama will do such a thing. He treasures me as a little sister, and that's only it.

*Huff, huff*

When onii-sama broke the kiss, I immediately stood up pressing my fingers unto my lips.

"So, this is your choice onii-sama? Well then, if you'll excuse me." I quickly let my bangs cover my eyes and headed up stairs, he didn't stop me and just let me go. Like I stated in the choices whether he'll kiss me and I won't show any more affection to him, or he'll push me away and say that I'm disgusting…But either way, he chose the hardest choice for me to take. And that is….I won't show any more of my feelings for onii-sama.

That's it, and there's no way I could break that I gave onii-sama my word. I'll just try my hardest not to get jealous when another girl takes place as onii-sama's precious one, I'll try my best not to cry every night, I'll try to smile like I mean it and finally…I'll try my best not break apart.


End file.
